[CRIU] [PATCH 1/2] pie/piegen: make -f explicit parameter

[Cyrill Gorcunov]

On Wed, Feb 17, 2016 at 01:46:51PM +0300, Dmitry Safonov wrote:
> One may specify other parameters, but not 'f'.
> Piegen should output usage() instead of trying to open "file.o"
> as -f is explicit.
> 
> Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov at openvz.org>